单选题 The passage tells us that the most probable reason for the death of the mice in Ader's experiment was that ______.

A、 they had been weakened psychologically by the saccharin
B、 the sweetener was poisonous to them
C、 their immune systems had been altered by the mind
D、 they had taken too much sweetener during earlier conditioning

【正确答案】 C

【答案解析】作者写第三段的目的是为了证明他在第三段第一句里的论点"the mind can alter the immune response'’，他用Ader的实验这一实例米论证此论点。为了培养老鼠的条件反射，Ader给它们喂食糖精，同时注射能降低免疫力并可引起肚子疼的药物，但后来只给老鼠喂食糖精而不注射药物时，有些老鼠死亡，这允分证明老鼠的免疫系统已被其思想改变了，所以[C]是正确答案。